A power split transmission, in particular for a working machine such as a wheel loader, is known from DE 10 2007 047 194 A1 and has a hydrostatic power branch and a mechanical power branch. The power branches are added by means of a summing transmission, wherein a reversing transmission is connected upstream of the summing transmission and a gear shifting transmission is connected downstream of the summing transmission.
Two driving ranges for forward driving and two driving ranges for reverse driving can be provided by means of the power split transmission, within which driving ranges the gear ratio of the power split transmission can be continuously varied by means of a hydrostatic device. The driving ranges can be switched by disengaging a shift element that is engaged and by engaging a shift element that is disengaged.
Disadvantageously, a shift element designed to provide a second driving range of the power split transmission is arranged on a hydrostatic shaft of the hydrostatic device, and therefore a connection of the hydrostatic shaft to a mechanical power branch requires a complex design. This is the result, among other things, of the fact that the hydrostatic device is normally supported by means of an elastic rubber bearing device for vibration damping and therefore an axial offset that varies during operation must be compensated by an appropriate jointed connecting device in the connection region between the hydrostatic device and the mechanical power branch. However, without additional design measures, this permanent compensation in turn causes excitation of vibrations to an undesired extent in the region of the shift element arranged on the hydrostatic shaft and an increase in the tendency to sway.
Furthermore, the power split transmission is characterized by a high installation space requirement due to the arrangement of the shift element on the hydrostatic shaft, because the two hydrostatic shafts of the hydrostatic device must be arranged at a certain distance from each other so that the installation space required for installing the shift element on the hydrostatic shaft can be provided.